Photochemical reactivity of 2-azido-1,3-thiazole and 2-azido-1,3-benzothiazole: a procedure for the aziridination of enol ethers

Direct irradiation of a mixture of the azido–tetrazole tautomers of 2-azido-1,3-thiazole and 2-azido-1,3-benzothiazole in toluene solution gives products arising from the intermediate nitrene, which in turn undergoes ring opening in the case of 2-azido-1,3-thiazole to give a polymer, and dimerization in the case of 2-azido-1,3-benzothiazole to give [1,3]benzothiazolo[ 2,3:3,4][1,2,4,5]tetraazino[6,1b][1,3]benzothiazole in low yields. When irradiation is performed in the presence of methyl acrylate or various enol ethers, aziridination of the double bond is observed, with good yields in the case of enol ethers. Among these, 1-(6-methyl-3,4-dihydro-2H-pyran-2- yl)ethanone undergoes aziridination with complete diastereoselectivity to give the (1RS,3RS,6SR) diastereomer.